The present invention relates to a towing vehicle controller on a towing vehicle, such as a commercial vehicle tractor, that controls the air brakes of a towed vehicle, such as a commercial vehicle trailer, and a method of providing brake control. More specifically, a towing vehicle controller and a method for transmitting a control air signal from a tractor air brake system to a trailer air brake system based on stability conditions of the tractor is disclosed.
The trailer air brake system receives supply and control air from the tractor air brake system. The trailer air brake system receives the supply air when the operator actuates the trailer supply valve in the tractor cab. When the operator actuates the foot brake valve in the tractor, a control air signal is transmitted to the trailer to actuate the trailer brakes. Tractors can be equipped with one or more automated braking systems, for example, an antilock braking system (ABS), an automatic slip reduction system (ASR), a roll stability control system (RSC) and/or an electronic stability control system (ESC) in order to stabilize the vehicle in critical driving situations. By means of ABS, RSC/ESC and ASR systems, the brake pressure at individual tractor wheel end brakes is controlled independent of the operator such that locking, spinning or lifting of the wheels is avoided, and vehicle directional instability is mitigated. An ESC controller, such as the Bendix® EC-60™ advanced controller, can perform the functions of ABS and ASR on the tractor and control the transmission of the control air signal to the trailer. The trailer braking system may be equipped with an ABS or RSC system, or no electronic control system, which affects if and how the ESC controller on the tractor communicates with the trailer braking system.
Tractors may also be equipped with automated cruise control systems (ACC), such as the Bendix® Wingman® adaptive cruise with braking system or a collision mitigation system (CMT) such as the Bendix® Wingman® Advanced™ collision mitigation technology. An automated deceleration request is received by the ESC controller when the ACC or CMT system determines that the tractor is advancing too closely to a target vehicle. The ESC controller responds to the automated deceleration request first by de-throttling the engine, then applying the engine retarder. Finally, depending on the deceleration value determined as a factor of the automated deceleration request, individually applying the wheel end brakes on the tractor.
A control air signal is sent from the tractor to the trailer based on the deceleration value; however the attached trailer may or may not be equipped with an ABS or RSC system. In order to accommodate a wide variety of tractor-trailer combinations, the ESC controller on the tractor is generally programmed to transmit a control air signal to the trailer as if the trailer did not have an ABS or RSC system. Therefore, depending on the particular tractor-trailer arrangement and the electronic devices available on the trailer, the braking response of the trailer brake system may not result in optimal braking performance for the particular automated deceleration request and driving conditions.
For the foregoing reasons, there is a need for a new and improved apparatus and method which addresses the above-referenced problems.